Kiss One Another, Die For Each Other
by SereneCalamity
Summary: There were several ways to unwind after a fight...Cizzy.


_Okay, I'm pretty sure we can all admit that Izzy is fucking hot, and I couldn't help but feel the need to write this oneshot._

 _Disclaimer: I do not own the characters, or the title of the song, which comes from Demi Lovato's_ Cool For The Summer.

"Izzy!" Alec Lightwood shouted, and his sister's wide eyes turned toward where he was looking at a vampire that was coming right in her direction. Isabelle Lightwood flicked her wrist, the electrum whip that was coiled around her arm sliding off quickly, and she lashed it out at the vampire. It looped around the vampires neck and tightened securely when she jerked her hand. She was about to pull out her seraph blade and lunge it into the vampires heart when Clarissa Fray appeared, slashing out with her blade and decapitating the vampire.

"I had that," Isabelle raised an eyebrow at Clary.

"I know," Clary smirked at her before running off to join Jace Herondale. Isabelle followed her with her eyes before another two vampires were coming her way, snarling and fangs showing. It didn't seem as though there were many vampires left—Alec was finishing off one, and Clary and Jace were fighting back to back with another two. Isabelle drove her seraph blade into the vampire who was attacking her brother, Alec slicing off it's head, and the siblings smirked at each other as Jace and Clary killed their vampires and gave each other quick once overs, making sure they were okay.

The four Shadowhunters were about to step out of the abandoned warehouse, Jace leading the way and Isabelle bringing up the rear when Clary's head twitched to the side. Isabelle's step faltered, wondering what the red head had heard, when Clary suddenly spun around and shoved Isabelle out of the way when a last vampire lunged forward, fingers curled into claws. They scratched deep into Clary's neck, clearly intended to get the top of Isabelle's spin and tear viciously if the woman had still be standing there. Isabelle faltered, but recovered quickly, slinging her whip around both wrists of the vampire while Alec decapitated it.

"Shit," Jace leaned in to touch Clary's neck, examining the scratches. "Not deep, they'll heal quickly." Clary nodded, and Jace turned to Isabelle. "You good?"

"I'm fine," Isabelle nodded, although her eyes were fixed guiltily on Clary. "I didn't even hear it."

"It's fine, that's why we're a team," Clary nudged her with her elbow and they continued out of the warehouse again. There were tears in their clothes and Clary and Alec both had blood spattered on their clothes; Alec from a slash on his arm and Clary from scratches on her neck. This particular nest of vampires had been feeding on humans, and the Institute had sent the team of four in to take them out. They weren't the worse nest that they had faced, most of them had been younger and not particularly skilled at defending themselves or fighting.

"Not a bad evening," Jace smirked as he snapped his seraph blade back against his belt. "I'm feeling like we still have time to go out and catch that party at Si and Raph's."

"Really?" Alec grunted as they headed toward the motorcycles that were parked on the other side of the road. "You don't just, I don't know, maybe want to head back to the Institute and call it a night? We did just kill over fifteen vampires, that calls for a bit of rest, right?"

"As if you're going to rest," Jace rolled his eyes at Alec. "We all know you're just going to take a portal to Magnus' and get it on with your man." Alec just pursed his lips but didn't reply. "What about you guys?" He looked over at Isabelle and Clary, both of whom were climbing onto their own bikes. "You wanna come? I bet if we get some more of that laced alcohol we can get Simon to do another song and dance routine to Destiny's Child." Isabelle smirked at that but Clary just narrowed her eyes.

"You be nice," she told him with a glare.

"Then maybe you should come with me and make sure I'm nice," Jace tried to wheedle.

"No, but I will give Raph a heads up, and you know that if you're an asshole to your boyfriend, he's got no problems with planting ducks in your room," Clary grinned at the horrified look on Jace as he remembered the last time he had pulled a prank on Simon Lewis, and Raphael Santiago had responded on behalf of his boyfriend.

"I don't know why I'm friends with the lot of you," Jace grumbled under his breath. The other three grinned at each other before pulling on their helmets and starting the trip across the city. The New York Institute was quiet, given it was almost one in the morning, and they all went their separate ways; Alec to the armory before he did exactly what Jace had said he would do, take a portal to Magnus' apartment. Jace to quickly report in the result of their mission so that he could leave for Simon and Raphael's party. Isabelle to the kitchen because the girl could eat her weight in food, especially after a mission. And Clary headed up the stairs to where their rooms were, planning on taking a long shower.

Not too many Shadowhunters actually stayed at the New York Institute. The Lightwoods did when they were in the city, but most of the time, Maryse, Robert and Max Lightwood were travelling, never staying in one place too long. Jocelyn Fray had moved out of the Institute once she and Luke Garroway had finally gotten together, and the team of four made up of Jace, Alec, Clary and Isabelle were the predominant Shadowhunters, so unless they were on call, a lot of the other employees lived off site.

That totally worked for the four, because it meant they got the nicest rooms, all with adjoining bathrooms.

Clary stripped out of the shirt she was wearing, sighing when she looked it over and saw it was torn beyond repair from where she had been thrown against some broken furniture and it had gotten caught in her clothes and ripped. She went through a ridiculously amount of clothes, but she wasn't going to complain out loud about it, because Isabelle would probably just suggest that she start wearing more spandex, like the raven haired girl did. When she was down to just her bra and underwear, Clary picked up her steele and traced over the healing rune on her skin, wincing at the burn, but it faded quickly.

She walked in to her adjoining bathroom, turning on the shower and setting about brushing her teeth and untangling her hair. She finished undressing, and before she got into the shower, she checked her neck in the mirror that was quickly steaming up. The scratches that were caused by the vampires claws were already fading and the skin was beginning to knit back together, helped by the rune. She took off her bra and underwear and tossed them toward the clothes basket in the corner of bathroom before stepping into the shower.

The hot water felt _so good_ running over her shoulders and down her back, wetting her hair and cleaning off the sweat and grime of the fight. It had been nowhere near the most grueling fight they had been in—not even close, but her and Alec had been training hard this morning, and Alec wasn't known for going easy. So even before they had gone out in search of the vampires, her body had felt battered. Clary was lathering up her hair with shampoo when the bathroom door opened behind her.

She didn't bother turning around—she knew who it was.

Isabelle didn't waste her time undressing, opening the glass door for the shower and stepping in. Clary's body was slippery with water and citrus body wash, and Isabelle softly ran her hands down Clary's arms before resting on her hips. The dark haired girl leaned forward and pressed a light kiss to Clary's shoulder before leaning against her, resting her chin on Clary's shoulder.

"Thanks for having my back in there," Isabelle murmured, voice barely loud enough to be heard over the running water.

"You know I'll always have your back," Clary replied quietly, tipping her head back slightly and then turning it so she could press a kiss against Isabelle's temple. "Did you finish off all the ice cream downstairs, or did you leave some for the rest of us?"

"Uh, well...You know I can go a little overboard when it comes to that raspberry swirl shit." Clary felt Isabelle's lips turn upward in a smile as her girlfriend turned her head so that her face was pressed against the red heads neck. Isabelle's lips pressed firmer against Clary's neck, until there was no denying that it was a kiss. Especially when Isabelle pulled her lips back so that her teeth scraped against her throat, just underneath where her injuries were healing.

"Is this your way of making it up to me that you finished my favourite ice cream?" Clary asked with a little admonishment to her voice, although she tilted her head to the side to give Isabelle better access. Isabelle smirked before she bit down gently on the tendon in her lovers neck, sucking on the skin just hard enough to send a shiver of pleasure-pain through the red head.

"Maybe," Isabelle mumbled as she shifted her kisses downward, to the juncture of Clary's neck. "And a thank you for saving my ass." Clary let out a huffing noise that was probably meant to be a laugh, but it was the same time that Isabelle's hands had lifted from her hips to cup her breasts and tug at her nipples. Clary pushed her ass backwards, arching her back out so that she pushed her its harder into Isabelle's hands. Isabelle's fingers moved skillfully—knowingly—over Clary, thumbs flicking at her nipples which were already swollen into hard buds. Isabelle's fingernails caught on the sensitive nubs and Clary's body jerked backwards.

"Not in the mood for teasing tonight, Iz," Clary grumbled as Isabelle ran the tips of her fingers underneath the heavy underside of Clary's breasts.

"Okay, baby," Isabelle whispered, one of her hands staying on Clary's chest while the other one slid over her taunt stomach and down toward the centre of her legs. Clary's body was slick with water and her body wash, and the combination of that along with Clary's natural arousal between her lower lips made Isabelle's fingers so easily slide in circles around Clary's clit. Isabelle was watching her movements, looking over Clary's shoulder and down at what she was doing. Clary's hips were jumping forward as Isabelle's fingers began to move faster around the little nub, and she let out a throaty moan that filled the shower.

"Shit, Iz..." Clary sighed as she bent one of her arms at an awkward angle so that she could grab a chunk of Isabelle's hair and give it a hard pull. Isabelle whined at the feeling, the jerk sending hot spikes of heat to her own groin, and she thrust forward against Clary's pert ass. Isabelle wasn't teasing her—not in the way that she sometimes could—but she wasn't sinking her fingers into Clary's heat to give her a quick orgasm either. Clary's hole was clenching around nothing, hips rutting forward, wanting more from Isabelle than she was giving. Isabelle bit down on Clary's shoulder again, not releasing the tender meat from her mouth as she kept moving her fingers, only applying pressure every second or third rotation directly to Clary's clit.

It didn't take long, even with Isabelle's fluttering touches rather than direct pressure, and then the red head was coming, a rushing sound thick in her ears as Isabelle toyed with her for a little longer, dragging out the feeling of her orgasm. Clary's body was shuddering against the dark haired girls, and her knees felt a little wobbly, glad that she could trust Isabelle to hold her up.

After a minute, she was spinning around, her hands shoving at Isabelle's shoulders and pushing her against the wall. Their lips came together for the first time that evening—actually, it was the first time for the whole day, now that Clary thought about it, because they had both been busy. The kiss was messy and their teeth bumped once or twice, their bodies sliding against each other, both slippery and slick, and Clary wasted no time in pressing one of her thighs between Isabelle's legs, lifting it up so it was hard against the apex of Isabelle's legs.

"Shit," Isabelle huffed out a breath, momentarily pulling away from Clary's lips to shuffle from side to side until her lower lips were spread, and then her clit was in contact from Clary's thigh.

"That's it, Iz," Clary murmured, nipping at Isabelle's lips as she moved her thigh back and forth, grazing Isabelle's clit each time, Isabelle writhing until she was practically riding Clary's leg. Clary's tongue dipped between Isabelle's lips, playing with her tongue and reaching down to take Isabelle's ass in her hands. Isabelle whined at the way Clary's small hands encouraged her to keep relentlessly moving against her leg. Isabelle's kissing was more heavy breaths and knocking teeth as she got closer to her orgasm.

Her hips bucked, tipping forward so that she could grind her clit against the red heads thigh, pulling away from Clary's mouth as her body convulsed. Clary smiled against Isabelle's collarbone, licking at the soft skin and then sucking a mark as Isabelle let out a high pitched cry as she climaxed. The two girls leaned against each other, Clary's face pressed against Isabelle's chest and Isabelle leaning her forehead against Clary's hair.

"This is totally fine as a thank you for saving your fine ass," Clary mumbled. "But you better replace that raspberry spiral ice cream by tomorrow night." Isabelle let out a laugh and nodded.

"Sounds like a plan," she murmured. "Also, I'm getting your body wash all in my eyes, so let's hurry up so we can go to bed." Clary grinned and pulled back, framing Isabelle's face with her hands and giving her one last kiss.

 _So? Let me know what you think :)_


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